Non-small-cell lung cancers (NSCLC) account for 85% of lung cancers and are mostly diagnosed at advanced stage. Drugs interrupting immune checkpoints, such as anti-CTLA-4, anti-PD-1, anti-PD-L1, have proven to unleash anti-tumor immunity and mediate durable cancer regressions in a portion of patients with NSCLC. Epithelial-to-mesenchymal transition (EMT) is a developmental process that enables reprogramming of polarized epithelial cells towards a mesenchymal phenotype with migratory and invasive properties. EMT has been involved in escape from oncogenic-induced senescence, resistance to chemotherapy and development of metastatic disease. Moreover, EMT promotes cancer cell plasticity and favors their adaptability to selective pressures. Here we made use of in silico approaches and further in vivo validation to evaluate the potential role of EMT as a major escape mechanism to tumor immunosurveillance in NSCLC. We performed an initial in silico analysis to assess the expression of immune checkpoint ligands (ICPLs) in 129 NSCLC cell lines (CCLE), in relation to their EMT status defined by a 72-gene EMT signature that was previously reported in NSCLC. Unsupervised hierarchical clustering analysis revealed that the expression of selected ICPLs was associated with the mesenchymal or epithelial phenotype. In particular, CD70, a member of the tumor necrosis factor superfamily, was significantly associated with the mesenchymal status (p < 0.001). We identified an E-box sequence (CANNTG) in CD70 gene promoter thus suggesting the possible regulation of CD70 by ZEB1 and/or SNAI. We extended the in silico analysis to a set of 488 adenocarcinomas (ADC) and 501 squamous cell carcinomas (SCC) from the TCGA and confirmed that CD70 expression was associated with a mesenchymal status (q-value <0.001). In a set of E-like (H441 and H1650) and M-like (H23 and HCC44) NSCLC cell lines we validated the association between an increased level of CD70 by flow cytometry and the mesenchymal status. Expression of CD70 by immunohistochemistry was observed in 5/51 lung ADC (10%), 6/45 (13%) lung SCC, 16/26 (63%) pulmonary sarcomatoid carcinomas and 2/10 (20%) small cell lung carcinomas. Interestingly, in pulmonary sarcomatoid carcinomas, CD70 expression was closely associated with the mesenchymal component. Our results suggest an association between the expression of CD70 and the mesenchymal phenotype, thus shedding light on the potential role of CD70 in immune escape of a subset of NSCLC.

Citation Format: Sandra Ortiz-Cuaran, Aurélie Swalduz, Maria A. Albaret, Christine Menetrier-Caux, Véronique Haddad, Arnaud Paré, Geneviève De Souza, Anne P. Morel, Maurice Pérol, Christophe Caux, Sylvie Lantuejoul, Alain Puisieux, Pierre Saintigny. CD70 immune checkpoint ligand is associated with the epithelial-to-mesenchymal transition in non-small cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2320.